Breaking of oil-water emulsions



Patented` May V7, 193,;`

J ohn CharlesWalkenv Eldorado, Kans., assigner, l by mesneassignmentmtoThe Tretolite Com#` y u pany; Webster Groves, Mo., ai corporation ofMissouri 'pplication September 2,

1921, vserial No. 49ans y A16 claims. (01,"*196-4) invention remesa thebreaking-of ou- Water emulsions, and more particularlyto a methfhod of*treating petroleum oil containing emulsion of oil and water to breakthe emulsion and sepa- 5 rate the'water fro'mthe oil.,` u

l u The petroleum oil producing strata ink most lo``- calities haveWater or brine associated with the o il. When the brine isagitated withthefoil, as is commonly donejjby pumps,;particularly defectivelyoperating pumps; anA oil-water emulsion is formed. Thebrineformsxthe`disperse phaseh of l the emulsion, `and is distributed in the oil asparticles varying invsize-from large drops to those of microscopic size,theparticles being surrounded by films of Oil; e fi v" l'I'hefpresenceof emulsions inpetroleum oil i's undesirable because theWet oils or oils containments tend to show, however, that/1pernianentiyemulsions may be made by agitating/oil with dis` tilled water, or with a-saltlsolution whichdoes not 4contain alkaline earth salts.lvlo'reover,'prac-l tically all: brines associatedgwith :i petroleumyoils contain a sufficient quantity of salts such asV the chlorides,sulphates `andcarloona/tes of calcium and, magnesiumg ,to formvpermanentemulsions withsome kinds of ,oi1s.', Also, manyof 'the emulsions containbrines of approximately the ,samey calcium and magnesiumcontents, but they vary quiteyvidely intheir1 resistance to breaking orsplittingtreatment; These facts"l appearuto indicate that thedifferencein emulsions formed in ing emulsions cannot be distilled or renedwith lthe Water in them. The presence of water-inoil undergoing distillationcauses th'e stills to .frothand thuscontaminates 'tiie"distillates.Accordu-ingly,V the reiineries and` tlfepipe linecompanies refuse to buyoil which-has more-fthana predetermined amount therein.

VThe water-in-oil manyr-gdiierent treatments have' beenA used` to vbreakthef'diierent emulsions;` The theory `has been presented that thediiferencein emulsions is emulsions formed from petroleums in different`localities-vary quite widely,-and i of a waterin-oil emulsion Y v 1 awater mixtureof benzenesulphozstearicacid, "which mixture is 1preferablyin the form of'anl different localities depends fmore ori the dijerevntcharacters pt the oils than upon the differentv l characters of thebrine'sassociated vwith the oils.

`The object iof thepresent inventionis to provide a method by.whichwaterfimoil emulsions maybe effectively broken, irrespective of thenay formed. t ITo dehydrate oil in accordancewith the present invention,the Wet oil vis thoroughly-mixed with emulsion.` The mixture is thenallowedto stratify 2o `tureof oils andjbrines ot whichlthe emulsionsare" i and the water removedfrom the oi1.` Y Dehydration u maybe`carried out at prevailing atmospheric'A temperatures, but it ispreferred to heat thewet oil to a temperature ot from 90,F1to150.F.1when 1 due to the Ydiierence in'chemical compositions 013-.

the-`brinesassociated vwith the oils.v` There appears to beno doubt`that the 4constituents of n "brine, particularly magnesiumandcalciumchlorides, tend to1form permanentemulsions,but

tests have shown that some oils will formnapermarient 'emulsionwithbrine containing a :low calcium and magnesium content as readily as withabrine containing a high calcium and magnesium content,` while other`oils willl formpermanent "emulsion with-either of ,theselbrines withgreat "difficulty i w Y Y, When relying upon the theory that thedifference in emulsions depends upon different ,characters of brines `inthe emulsions, certain chemi- 'cal treatmentsof thewet oily have beenused-:to -break the emulsions. :The chemical `reagents are* allegedtohave' water softening properties, and

when they `are 'brought .into contact with-the.

emulsions they aresupposed to precipitaterthe `salts in the brine andbreak down the disperse phase of the emulsions.

v"acters of thebrines inthe emulsions.` `Expert- Different chemical` re#agentstherefore have-been usedto procipitate` 1 the salts; in accordancewith' the. different char-` it is Vbeing mixed with the benzenesuipho-ste'aric acid becausev heatl increases thel-effectivenesslof `thetreating agent, decreases the viscosity of the oil, aids in lowering thesurface tension of the ,was

ter, anddecreases the timerequlred yfor stratii-V cation.l 4 u u u l, fIn the. accompanying drawing is diagrammatically illustrated anapparatus in which the preo l `ierred` method #of the invention maybecarried To carry out themethod above referred to in the apparatus shownin thedrawing, oilcontai'ninga water-in-oil emulsion is. led in througha pipe Il) and passesinto a proportlonating ,device |2.where,it is mixedwith apredetermined quan` tity of benzene sulpho-stearicY acid that isintroduced from one of a pair of chemical'tanks 14.

VThe mixture of thewet oiland the benzene sul-l 'pho-stearic acid isthen'carried by meansofa pump I6 through apipe I'intofaheater 20. The

oil isheated in therheater 20 bymeans of steam admitted through aline 22and the exhaust steam from the pump I6 may be also ,passedy into the4heater .20. `From the `heater A2li the mixture of the oil'hasreached'the tank 44 lthe heat and the palm oil may be used. f

, Various experiments have shown that the'benunbroken emulsion arisingto the top of the tank.

The brine separating in the tank 28 is continuously drawn off'through anautomatic siphon, and `the mixture of oil and emulsion leaves the top ofthe gun barrel tank through a pipe 32 and passes into the bottom of a.heating tank 34 through a distributor 36. The mixture of wet oil and thetreating reagent 'is further heated in the heatingy tank '3.4 by meanscfa steam coil 38, and further stratification ofthe oi-land the emulsiontakes place. The water,set.free may be drawn Aoff through an voutlet`fl0,rand unbroken emulsion, together withthe oil, passes out of the topof'the tank34 through a pipe 4,2, andy is introduced intov the bottomofa settling tank 4,4. By the time ltreating agent have broken downsubstantially allofthe emulsion inthe oil and the mixture of oil andwater straties in the `tank 44. The water may be drawn off throughan-outlet 46 and the clear oil flows off from the top of the .tank "44through a pipev48; and may then pass to a.

storage or stock tank 5B.` y

With the apparatus outlined above it will be zseen that oil may*l becontinuously pumped 'vthroughthe treating apparatus and becontinuouslydehydrated. f Although it is preferred to use such acontinuous process, it is not lnecessary v that the apparatus shown inthe drawing be used to .obtain an electiv dehydration of the oil, `butany suitable apparatus maybe used by which the benzene sulpho-stearicacid may be thoroughly `mixed with the'oil and the treated-oil allowedto stratify to separate the water or brine therefrom.

v The benzene sulpho-stearic acid may be'prepared.4

in many different ways, but it is preferred to prepare this reagent bymixing oleicacidiwith benz ene in the ratio of three` parts of acid to33%- parts of benzene, and the resulting solution is then treated'atordinary temperatures'with concentrated sulphuric acid in the ratio offour parts of sulphuric acid to three parts of` the fatty acid byweight. Thesulphurlc acid is slowly added to the benzene-oleic acidmixture, while' the solutionis being' constantly agitated,land the tem-'perature of the solution is controlled to prevent sulphur dioxide frombeing liberated from kthe solution. When the sulphuric acid iscompletely absorbed the mass is washedv one or more times with water andis then in condition -to be used for treating water-in-oil emulsion.This aromatic sulpho fatty acid :is only slightly soluble in water andwill form an'emulsion with water. It is a heavy reddish brown viscousoil having an aromatic odor, and is quite stable. In place of the loleic acid the commercial red'oil and also oliverorzene'of the aromaticsulpho fatty acid mayV be replacedby toluol,xylol, phenol, ornaphthalene. The aromatic radical 'of the toluol', xylol, phenol,v ornaphthalene is attached to the sulphor fatty acid in the same mannerthat the lbenzene radical is attached thereto, and the reagents'containing these aromaticsmay be made in the same manner that thebenzene sulpho fatty acid is made. All of these aromatic compounds areeffective in breaking emulsions, but it is preferred to use the benzenesulpho fatty acid because it has a stronger `dehydrating effect. It isalso easier to handle and is cheaper to manufacture.

The quantity ofthe reagent which must be used in breaking emulsiondepends entirelyupon the character of theemulsion. If the emulsion isrecently formed it seems to break much more readily than an emulsionwhich has been standing in the air or in the bottom of an oil tank for aconsiderable period. The concentrated benzene ,sulpho fatty acid willbreak the most stubborn T15 of one per cent to -156 of-.one per cent byvolume `of the volume of emulsion tol be treated.

The action ofthe aromatic supho fatty acid in breaking the oil-water,emulsions appears to be more of aphysical or aphysical chemical naturethan a true chemical reaction. yExperiments indicate thatv the oil-Water.emulsion has the brine for thevdispersrefphase. The aromaticsul-l Yphofatty acid will form anA emulsion with water in which lthe: fatty acidthe disperse phase. .The disperse phasev of the -water-in-oil emulsion`has anegative charge and the disperse phase of the fatty acid-Wateremulsion appears to have a positive charge. The'treating reagenttherefore appears to act to neutralize the electrical charge of theywater-infoil .emulsion and allow the water to coalesce. kThe aromaticfatty'acid also appears togiveya marked change in the surfacev tensionof the oil-water interface which disturbs the equilibrium existingbetween the continuous andthe disperse phases, .and consequently tendsto break the emulsion. o v 'A It is possible Aalso that the presence ofthe ionized aromatic sulpho fatty acid acts as a catalyst indestroyingthe equilibrium of the emulsion, and thus causes the emulsionto break-down. Sulpho fatty acids have been shown by Ernst VIwitchell tohave a catalytic reaction when splitting rfats to form glycerine and setfree of fatty acid, and it may be that the sulpho acids actin a similarmanner in breaking down emulsions.

Experiments would appear to prove that the breaking of .emulsions bytheprocess described above does not depend upon ythe lpresence of `orthe chemical action on alkali earth salts. The benzene sulpho-stearicacid is notA a water softening agent, it does not break an emulsion byreason of theA removal by precipitation ofthe lcalcium and magnesiumsalts, and the presence of alkaline earth salts in the emulsion has nospecial significance in the applicationvof the process. l 1

While it is believed that the breaking of the oil-water emulsion withthearomatic sulpho fatty acid is dependent on an'action of a physicalnature, rather than upon 4a chemical nature, it is to'be understood thatthe invention isfnot based, dependent upon, or `limited to any theoryexcept `as specifically defined in the, accompanying claims. l

In the claims the emulsions are referred to as comprising oil and water.By the term water" it is intended to include thevarious brines or as a.Led fatty body,

in referring to the benzene.sulpho-stearic-acid,`

itis notto be understood .that this acid is.chemi, cally pure.` Thedehydration process' dcesnot 'require the use of 1chemicallypurereagentsyand preferably, the commercial constituents are used inthemanufacture of benzene sulpho-stearic acid. 'No 'attempt is made to`separate the benizeneA sulpho-stearic acidfrom kany ,by-product formedin the reaction, and therefore-the material which can be effectivelyused in the process may kcontain small amountsof unchangedor partiallychanged oleic acid,vbenzol andfsulphuric acid. `In defining thetreatingl reagent as benzene sulpho-stearic acid,fitis not tobeunderlstood that this is the exact structure of thereaction product ofthe benzenesulphuric acid `and "oleic acid used `in making thereagent.v4

`Cornrn'ercial or crude benzene'contains small amounts of phenol,`toluene and other impurities. Commercial or crude phenol containscresols.

lCommercial or crude .naphthalene Vcontains not only naphthalenebutlailso naphthalene homologues including monoanddi-methyl'naphthalenes, ethyl naphthalenes, as well as diphenyl,

indene, acenaphthene, cresols andother phenolic i bodies, and quinolinebases.

Twitchelll (above `referred to) has shown that when concentratedsulfuric acid in'excess acts on a mixture of a detergent-forming orsoapforming material, such as a fatty acid or a fatty oil,v(fatty oilsvsuch` as commercial red oil, olive oil, palm oil rand .the`likeconsisting chiey of fatty acid glycerides or esters), and a memberof the'aromatic series, such as naphthalene (polycyclic) benzene(non-hydroxy mono-cyclic) phenol (hydroxy mono-cyclic) etc., a partialunion or condensation takes place Abetween the aromatic, thedetergent-forming material,`

and the sulfuric acid. The sulfuric acid acts sulfonating, condensingand dehydrating agent. The product of the reaction has been yshown byTwitchell to consist of a complex mixture comprising a condensationproduct containing,-in chemically combined form,-an aromatic group, asulfonic group or Ygroups and a group. (Such condensation broadlycharacterized as a modisuch as the benzene sulfo-stearic acid abovedescribed); unacted on detergentforming or fatty materials (for examplecommercial oleic acid); unacted on aromatic bodies (for examplecommercial benzene and phenol); sulfuric acid; and other more or lesscomplex byproduct may be products of the reaction, including fattymaterial suchas oxystearicl acid and fatty anhydrides,

, sulfo fatty acids, such as stearo-sulfuric acid,

and aromatic sulfonic acids such as benzene sulfonic acid andnaphthalene sulfonic acid.

The preferredv form of the invention having been thus described, what isclaimed as new is:

' forming (See VVpages 22 to 26 of the Journal of the American mixtureof commercial benzene andcommercial v oleic acid.

3. A method of breaking emulsions of water-inoilacornprising mixingtherewith a reagent containing benzene sulfo-stearic acid, benzene,oleic acid and other products formed during-the sulphonation of amixtureof commercial benzene and commercial oleic acid,\said reagent containingsubstantially no free mineral acid. c 4. Amethod of breaking emulsionsof water-inoil comprising mixing therewith the reaction Vproductfof theincomplete `sulphonation of a mixture of commercial benzene andcommercial oleic acid.

5. A process for breaking petroleum emulsions, characterized bysubjecting the emulsion to the action of a demulsifying agent consistingof a mixture comprising a condensation product of a fatty body and anon-hydroxy-mono-cyclic aromatic group, and other complex bodies.

6. A process for breaking or separating petroleum emulsions,characterized by subjecting the emulsion to the action of a treatingagent consisting of a mixture comprising a condensation productcontaining a sulpho-aromatic, soapforming acid and other complex organicbodies, produced by sulphonating a mass composed of an organicsoap-forming acid and an aromatic compound in which the proportion ofaromatic molecules to soap-forming' molecules is greater than the ratioof one to one.

'7. A process for breaking or separating petroleum emulsions,characterized by subjecting the emulsion to the action of a treatingagent consisting of a mixture comprising a condensation productvcontaining a sulpho-aromatic, soapacid and other complex organicbodies, produced by sulphonating a mass composed of a fatty acid and anaromatic compound in which the proportion of aromatic molecules to fattyacid molecules is greater than the ratio of one to one.

8. A process for breaking petroleum emulsions,

characterized by subjecting the emulsion to the l action of ademulsifying agent comprising a crude reaction mixture containing acondensation product of a fatty detergent-forming group, a monocyclicaromatic group, and a sulfonic group or groups.

9. A process for breaking petroleum emulsions, characterized bysubjecting the emulsion to the action of a demulsifying agent consistingof a mixture containing a condensation product of an organicdetergent-forming group and an aromatic group, and other complex bodiesproduced by sulfonating a mixture of an organic detergent-formingcompound and an aromatic compound.

10. A process for breaking petroleum emulsions, characterized bysubjecting the emulsion to the action of a demulsifying agent comprisingand a soap-forming body.

11. A process for breaking petroleum' emulsions, characterized bysubjecting theemulsion tothe action of a demulsifying agent, comprisinga mixture consisting of a condensation productl containing asulfoaromatic soap-forminggroup, and other complex organic bodies produced bysulfonating a mixture of an aromatic compound 12. A process for breakingpetroleumA emulsions, characterized-by subjecting the emulsion to theaction of a demulsifying agent comprising a condensation productcontaining `an aromatic fatty group, and other complex organic bodiesformed by interaction between a fatty compound, an aromatic compound andsulphuric acid.

13. A process for breaking petroleum emulsions, characterizedl bysubjecting the emulsion to the action of a demulsifying agent,consisting of a mixture of 'a substantial quantity of a sulfoaromaticfatty compound and other fatty and aromatic bodies.

14. A process for breaking petroleum emulsions, characterizedby'subjecting'the emulsion to the action of a demulsifying agentconsisting of a mixture containing a fatty acid, a sulfo aromatic,l

a sulfo aromatic fatty acid, and a nonsulfonated aromatic substance. 15.A process for breaking or separating petroleum emulsions, characterizedby subjecting the emulsion to the action of a treating agent consistingof a mixture comprising a condensation product containing asulpho-aromatic, soapform ing acidand other complex bodies, produced bysubjecting an organic soap-forming acid in which the carboxyl group isblocked and non-reactive,

to the action of anxaromatic inthe presence of a sulphonating agent. f

16. A process of breaking or separating petro- .leum emulsions,characterize-d by subjecting the emulsion to-the action of a treatingagent consisting of a mixture comprising a condensation productcontaining a sulpho-aromatic, soapforming acid and other complex bodies,produced by subjecting a fatty acid in which the carboxyl group isblocked and non-reactive, to the action ofan aromatic in the presence ofa sulphonating agent. JOHN CHARLES WALKER.

